A new approach to chemical modification protocols of Aspergillus niger and sorption of lead ion by fungal species

ABSTRACT

Biomasses of five fungi species (Aspergillus niger, Penicillium austurianum, Saccharomyces cerevisiae, Mucor arcindloides and Trichoderma reesi were evaluated for their uptake of lead ion from aqueous solution using batch systems. Both dead and live fungal biomasses were comparatively studied for their adsorption efficiencies. The effect of pH as one of the primary factors that influences sorption efficiency of metal ions in solution was also studied. Modification of the fungal biomass with the least sorption capacity was carried out using a four-step procedure. Three different modifying agents under the optimised experimental conditions were used. The percentage uptake of lead ion by fungi species ranged from Aspergillus niger 6.71-64.95 percent and 66.91-95.27 percent; Penicillium austurianum 44.47-98.85 percent and 75.57-94.21 percent; Saccharomyces cerevisiae 52.61-88.68 percent and 61.20-89.95 percent; Mucor arcindloides 83.78-93.13 percent and 62.91-97.65 percent and Trichoderma reesi 52.52-80.70 percent and 35.31-88.13 percent for dead and live biomass respectively. The influence of pH on metal uptake was evaluated at pH of 2, 4, 6 and 7. A regular pattern of sorption efficiency among the dead fungi species with respect to pH was observed and the percent adsorption decreased in the order pH 7 > 2 > 6 > 4 with the exception of Mucor (pH 7 > 2 > 4 > 6). Modified biomass of Aspergillus niger with oxalic acid, malic acid and ethylenediamine tetraacetic acid (EDTA) recorded 92.84 percent, 48.11 percent and 39.83 percent uptake of Pb respectively which correspond to 69.65 percent, 41.23 percent and 29.25 percent increase when compared to 28.18 percent of the unmodified biomass. These quantitative adsorptions demonstrate the potential application of modified biomass for the removal of Pb ion from aqueous solution.